By an odd chance I have only a few days ago been discussing this subject, in relation to plants, with Dr.Hooker, who believes to a certain extent, but strongly urged the little apparent extinction in the equatorial regions.

I stated in a letter some days ago to him that the tropics of S.America seem to have suffered less than the Old World.
There are many perplexing points; temperate plants seem to have migrated far more than animals.

Possibly species may have been formed more rapidly within tropics than one would have expected.

I freely confess that you have confounded me; but I cannot yet give up my belief that the Glacial period did to certain extent affect the tropics.
LETTER 354.

TO J.D.HOOKER.